Multiscale Structural Characterization of Biobased Diallyl–Eugenol Polymer Networks
Résumé
Biosourced eugenol-based polymer networks have a potential functionality for antibacterial coating applications. The presence of carvacrol, a phenol compound, exacerbates these properties. However, the relationship between the network structure and the macroscopic thermomechanical behavior is not known for these biopolymers. Thus, this work details a robust study of this relationship through a multiscale experimental approach combining Dielectric spectroscopy, DMA, Tensile testing and Time domain DQ 1 H NMR. It was shown that carvacrol has an influence on the molecular mobility of the materials. Namely it induces the appearance of a shouldering on the γ relaxation and a diminishing of T α. More surprisingly, up to 20% wt , carvacrol increases the elastic E and Young's E moduli. This observation can be interpreted as an increase of the crosslink density ν C of the networks. Time domain DQ 1 H NMR shows that the 1 residual dipolar coupling constant D res also increases. Thus, carvacrol seems to act as both a thermal plasticizer and a mechanical reinforcement, which may seem to be antagonistic trends. For carvacrol contents over 20% wt these properties diminish due to a saturation of this molecule in the networks and the onset of a phase separation. By combining the aforementioned techniques, it was proven that carvacrol linearly increased the measured crosslink density and thermomechanical properties by physically bonding to the networks through π − π interactions. These interactions would act as physical crosslinks. This work demonstrates that by correlating the results of various multiscale experimental techniques, a better comprehension of the structure-property relationship can be established for biobased functional polymer networks.
Domaines
Matériaux
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